Agitation of pulps and the like



March 6, 1951 E. D. DAVIS ET AL 2,544,301

AGITATION 0F PULPS AND THE LIKE Filed Feb. 24, 1948 31.7mm? mammal/15.JDEEFH sanafismam area,301

AGITA'FION OF PULP ZANDJ HELIKE tiloniof Canada: l1

Edward, Delbert" Davis and 'i't'ed Winnipeg, Manitohmyfianada', a.corpora "Application Feb-ma 24., 19481 S erialNo. 1034s 1 Claim. (01.259-433) This invention relates to an agitating device having particularvalue in the field of agitation of pulps in the processes of oreconcentrations by flotation procedures.

In the art of flotation concen ration of ores, it is common know edgethat agitation of the pulp for example with alkalizing agents, flotationagents, air or other agents is usually desirable to cause the mineralparticles to become receptive to the desired subsequent response infroth flotation. This agitation or conditioning is commonly effected bymechanical stirring using one or more impellers submerged in the pulpand mounted on a rotating shaft. Such impellers are commonly of thepropeller type such as used in marine propulsion, or four bladedbevelled cross impellers, or multiple stacked rotationally staggeredtwin blade arms of the type used in repulper machines.

The difiiculty with the known impellers is that in order to obtain asatisfactory degree of agitation, they involve either an inordinatelylarge consumption of power to drive the impellers, or excessive wear ofthe impellers and in some cases are subject to both of these importantdisadvantages.

According to the present invention there is provided an agitating devicewhich overcomes these disadvantages and comprises in general terms arotatable shaft, and mounted thereon at least four loop members ofsubstantially the same configuration, each loop member being alignedwith another to form a closed hoop member, and at least one loop memberbeing spaced at any point therein closer to the shaft than thecorresponding point in another 100p member whereby the loop memberstravel at least two discrete paths on rotation of the shaft.

In the preferred, form of the invention there are two=such hoop membersmounted at 90 to each other, and one hoop member is smaller than theother only by an amount such that the path travelled by one clears thattravelled by the other. The two loop members of any hoop member may beidentical in size, or the four loop members maybe successivelydimensioned so that the four loops will travel four distinct paths.

According to a further feature of the invention each loop is offset fromthetrue tangential position in relation to the path which it travels,points in the leading edge of each loop member being more remote fromthe shaft than corresponding portions of the trailing edge.

Theinvention will now be described with reference to the accompanyingdrawings in which Figure 1 is an oblique view of an agitating deviceaccording to the invention,

Figure 2 is a plan view with the driving shaft removed,

Figure 3 is an elevation with the driving shaft removed, and

Figure 4 is an elevation with the driving shaft removed taken at toFigure 3.

The device comprises a shaft II) adapted to be rotated by suitabledriving means and loop members II, I2, I3 and I4 which in the form ofthe invention illustrated are mounted on hubs l5 suitably keyed to theshaft I0.

As illustrated, the loops are arranged in aligned pairs to form hoopmembers which may be circular, or of any other desired shape, providedthat all of the loop members are of substantially the same configurationso that the path travelled by one loop member will not cut across thepath travelled by any other loop member.

The two loop members of each pair forming a hoop member are of the samedimensions, but one hoop is smaller than the other. Thus, any point ineach of the loop members II and I2 is spaced closer to the shaft I0 thanthe corresponding point in either of the loop members I3 and I4 so thatwhile the two loop members II and I2 travel the same path as each otherand the two loop members I3 and I4 travel the same path as each other,the two paths travelled are distinct. They are, however, closed and itis an important feature of the invention that the hoop member formed bythe loop members I I and I2 be smaller than the other hoop member onlyby an amount such that the path travelled by each hoop member clearsthat travel ed by the other.

As illustrated in Figure 2, the loop members according to the preferredform of the invention are twisted or skewed so that the leading edge I6is spaced farther from the shaft I 0 than the trailing edge II. It hasbeen found that the best results are obtained if the angle which thistwist or skew causes the loop member to depart from the true tangentialposition in relation to the path which it travels is of the order of 5at the central portion of each loop tapering to zero at each end whereit is connected to a hoop.

Instead of the two loops of an aligned pair being of the same size, theplurality of loops may be successively dimensioned so that each loopmember travels a path distinct from any other. There may, of course, bemore than two pairs of loop members.

What we claim as our invention is: 1 An agitating device comprising arotatable shaft, 3, first pair of loop members mounted on said shaft toform an outer hoop member, a second pair of loop members mounted on saidshaft to form an inner hoop member, said outer and inner hoops beingarranged at an angle of substantially 90 to each other, said inner andouter hoop members being circular in configuration and a twist of eachloop member decreasing gradually from a maximum at the central portionto zero at each end, said outer hoop being of greater diameter than saidinner hoop so that any point on said inner hoop member is located closerto said shaft than the corresponding point on said outer hoop member,the difference in diameter between said hoop members being uniform atall points 16 along their circumferences, and each of said loop membersbeing twisted so that points on the lead- 4 ing edge of each loop memberlie more remote from said shaft than the corresponding points on thetrailing edge.

EDWARD DELBERT DAVIS.

JOSEPH EUGENE GERMAIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 99,173 Earle Jan. 25, 1870131,600 Crocker Sept. 24, 1872 235,245 Hughes Dec. 7, 1880 1,290,333Pattison Jan. 7. 1919 2,076,975 Bach Apr. 13, 1937

